explain the type of weathering along with example
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Answer:
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Explanation:
Weathering
Weathering is the breaking down of rocks,
soils, and minerals as well as wood and
artificial materials through contact with the
Earth's atmosphere, water, and biological
organisms. Weathering occurs in situ (i.e.,
on site, without displacement), that is, inthe same place, with little or no movement,
and thus should not be confused with
erosion, which involves the transport of
rocks and minerals by agents such as
water, ice, snow, wind, waves and gravity
and then being transported and deposited
in other locations.Two important classifications of
weathering processes exist – physical and
chemical weathering; each sometimes
involves a biological component.
Mechanical or physical weatheringinvolves the breakdown of rocks and soils
through direct contact with atmospheric
conditions, such as heat, water, ice and
pressure. The second classification,
chemical weathering, involves the direct
effect of atmospheric chemicals or
biologically produced chemicals also
known as biological weathering in the
breakdown of rocks, soils and minerals.
[1]
While physical weathering is accentuated
in very cold or very dry environments,
chemical reactions are most intense wherethe climate is wet and hot. However, both
types of weathering occur together, and
each tends to accelerate the other. For
example, physical abrasion (rubbing
together) decreases the size of particles
and therefore increases their surface area,
making them more susceptible to
chemical reactions. The various agents act
in concert to convert primary minerals
(feldspars and micas) to secondary
minerals (clays and carbonates) andrelease plant nutrient elements in soluble
forms.
The materials left over after the rock
breaks down combined with organic
material creates soil. The mineral content
of the soil is determined by the parent
material; thus, a soil derived from a single
rock type can often be deficient in one or
more minerals needed for good fertility,
while a soil weathered from a mix of rock
types (as in glacial, aeolian or alluvialsediments) often makes more fertile soil.
In addition, many of Earth's landforms and
landscapes are the result of weathering
processes combined with erosion and re-
deposition.
Physical weathering, also called
mechanical weathering or disaggregation,
is the class of processes that causes the
disintegration of rocks without
important mechanism in deserts, where
there is a large diurnal temperature range,hot in the day and cold at night.
[3] The
repeated heating and cooling exerts stress
on the
gradient can be understood in terms of
stress or of strain, equivalently. At some
point, this stress can exceed the strength
of the material, causing a crack to form. Ifnothing stops this crack from propagating
occurs formed by the
weathering of wave actions
In pressure release, also known as
unloading, overlying materials (not
necessarily rocks) are removed (by
erosion, or other processes), which causes
underlying rocks to expand and fracture
parallel to the surface.Intrusive igneous rocks (e.g. granite) are
formed deep beneath the Earth's surface.
They are under tremendous pressure
because of the overlying rock material.
When erosion removes the overlying rock
material, these intrusive rocks are exposed
and the pressure on them is released. The
outer parts of the rocks then tend to
expand. The expansion sets up stresses
which cause fractures parallel to the rock
surface to form. Over time, sheets of rock
break away from the exposed rocks alongthe fractures, a process known as
exfoliation. Exfoliation due to
Chemical weathering
Chemical weathering changes the
composition of rocks, often transforming
them when water interacts with minerals to
create various chemical reactions.
Chemical weathering is a gradual andongoing process as the mineralogy of the
rock adjusts to the near surface
environment. New or secondary minerals
develop from the original minerals of the
rock. In this the processes of oxidation
and hydrolysis are most important.
Chemical weathering is enhanced by such
geological agents as the presence of
water and oxygen, as well as by such
biological agents as the acids produced by
microbial and plant-root metabolism.The process of mountain block uplift is
important in exposing new rock strata to
the atmosphere and moisture, enabling
important chemical weathering to occur;
significant release occurs of Ca
2+ and
other ions into surface waters.